Project19 Presentation

7/27/2019 Project19 Presentation

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High Speed Data Measurer for use

with Quantum Cryptography and

Laser Range Detector

By

Michael Noone

KanKan YuCharles Ruiz


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Outline

Introduction

Objective

Applications

Technology

Cost Analysis

Conclusion Q & A


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Introduction

High Speed Data Measurer used as a

component for a Laser Range Finder and

Quantum Random Number Generator.

Combination of high speed circuit design,

optics, and control logic to produce a Laser

Range Finder.


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Applications

High Speed Data Measurer

Laser Range Finder

Quantum Random Number Generator

Laser Range Finder

Computer Imaging Systems

Single use distance detector

Random Number Generator

For use with Quantum Cryptography


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Objectives

Design and build a high speed timing circuit Must find the time between rising edges of pulses

Accurate to approximately 50ps

Interface timing circuit to computer

Write control software to interpret data from timing circuit Design and build laser range finder using timing circuit

Use time of flight range finding technique

Use high speed laser driver

Use high speed receiver Receiver should filter out all wavelengths except for that of the laser used

Design and build a scanning mechanism that rotates the laserrangefinder skill in one or two axes


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Technology


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Project Construction

Cadsofts Eagle for schematic design and PC board layout

Advanced Circuits and ECE shop for board layout

Parts ordered from: Transducers Direct (timer chips)

Digi-Key Mouser

Newark

ECE shop

Professor Kwiat

Circuit boards hand soldered Hakko 936-12 ESD safe iron

Kester no clean flux pen

Kester no clean solder

fine tweezers for component placement


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In a nutshell

Timing

Circuit

Detector

Circuit

ScanningMechanism

Control

Module

Laser OpticsLaser Driver

Circuit


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Laser Driver Objective & Parameters

Objective

Drive the Laser Diode with crisp square pulses

Parameters High Speed Data In

Quick Rise and Fall Time

Drive 90 mA for Laser Diode

Low Noise


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Laser Driver CircuitConcept Art


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Board Layout


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Final Product


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Transmit Optics (Complete)

Requirements: Collimated beam

Optimum power match up with laser driver

Wavelength matching up with receiveroptics

Fast rise time


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Receiver Optics (Incomplete)

Requirements:

Detection of scattered beamfrom objectand discrimination of ambient light.

Accurate and constant time spent onsending signal to timing circuit.

Fast rise and fall times that allow for higher

precision in laser range finder.


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Optics Results


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Timing Circuit Objectives

Circuit that can measure time lapsed between rising edges oftwo pulses

To be used for measuring time of flight of laser pulses Measure the time span between outgoing laser pulse and incoming

received laser pulse Goal is 1cm resolution

For quantum cryptography random number generator: Needs to measure time span between pulses all on the same line

Needs approximately 200ps resolution.

Needs to be ready for a new sample within about 20ns of receivingprevious sample


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Resolution

For Laser scanning circuit, we want 1cm resolution

Speed of light is 299792458 m/s

Thus, we theoretically need resolution of .01 * 2 *

299792458 m/s = 67ps This makes assumption all other components are perfect

Since all components are not perfectwe need better than 67ps

resolution

For Prof. Kwiats quantum cryptography circuit, weneed about 200 ps resolution, so this easily falls

within laser range finder design parameters


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Timing Circuit Considered

Discrete timing circuit

Acam TDC-GP2

Acam TDC-GPX


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Discrete Timing Circuit

Start signal latched D-latch so that mosfet turns on,charging C through an RC circuit

Stop signal un-latches D-latch so that mosfet turns

off, stopping the charging of C ADC then reads in voltage across capacitor, and then

can find amount of time spent charging capacitor byextrapolating it from Vc = 5 * (1-e^(t/(RC) ) )

Unfortunately, propagation delay and gatecapacitances of components completely destroysaccuracy and resolution of such a circuit


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Discrete Timer Schematic


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Acam TDC-GP2

Special purpose timing chip designed to measure the amountof time that elapsed between a start pulse and a stop pulse

Somewhat low cost - $28/chip

50 ps resolution

Very small QFN 32 package

Fairly simple external components needed

SPI interface Runs at up to 25MHz

Would take approximately 1s to read out data Fast enough for laser range finder

Too slow for random number generator


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Acam TDC-GPX

Special purpose timing chip designed to measure theamount of time that elapsed between a start pulse anda stop pulse

High cost - $187/chip 10 ps resolution

100 TQFP package

Very complicated external components needed

High speed parallel interface Easily fast enough for both random number generator and

laser range finder


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Final Decision

Our choice:

We chose to use the Acam TDC-GPX

Though the other two circuits considered would have been

considerably easier to design, build, and debug, this wasthe only way for us to meet Prof. Kwiats needs

Parameters for TDC-GPX schematic design:

Ultra clean power supply

Minimal part count

Parts with small footprints

Singled ended and differential start and stop signals


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Final schematic:


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Parameters for TDC-GPX board design

Maximize size and integrity of ground plane

Minimize noise on signal traces

Minimize all trace lengths, especially signaland analog traces

Traces that have to cross over each other

should be perpendicular

Match impedances and trace lengths of

differential signals


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Final board design


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Final board top


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Final board bottom


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Final PCB Top


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Final PCB Bottom


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Control Module (Complete)

Requirements: Provide successful start up

of laser driver and TDC-

GPX.

Provide successfulinteraction between the

laser driver and the TDC-

GPX.

Program onto a Spartan-3

for this interaction

Serial communication with

computer to send timing

information.


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Control Module -- Timing Circuit Pseudo

Code &Laser Driver State Diagram


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Laser Driver State Machine

High State

Bump Edge Counter (Rising)

Low State

Bump Edge Counter (Falling) 10 Pulses sent stage

00 Error Code Fail State

Laser Shutdown State

TriggerLaser

Process Data

Start Over


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Control Module Results


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Cost AnalysisSoftware (COCOMO)Effort Adjustment Factor (EAF) Rating : 1.14

Organic Software Project

Coefficient a = 2.4

Exponent b = 1.05

Size of software = 6 K Lines of Code

Effort = [ a (Size)b ] (EAF) = 17.95 person-months Software Development time = Effort/people = 4.49 months

4.49 months * (60 hours/month labor) ($ 60 / hour) (3 people)

Labor Cost = $ 48.5K

Without Makelas proposed 2.5 estimation factor


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Cost AnalysisHardware Costs and

Labor Parts Cost : $377.33

Basic Electronic Components (Resistors, Capacitors, etc) - $35.00

TDX-GPX - $187.00

Vertical SMA Connector$5.94 Circuit Board - $33.00

Photodiode - $6.14

Laser Diode - $5.00

Spartan 3 FPGA - $100.00

AND 2870 - $5.25 Hardware Labor Costs and Estimation

(160 hours) ( $60/hour) (3 people)

Labor = $28.8K

Total Costs = Software Labor + Hardware Labor + Parts = $77677.33


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Success consists of going from

failure to failure without loss ofenthusiasm.

-- Winston Churchill


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Successes

Laser Driver Circuit Design and Layout

Transmit Optics

Timing Circuit

Control Module


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Shortcomings Laser Driver Circuit

High Speed Circuit

Extremely Sensitive

Receiver Optics

Breadth of work needed to build a proper receiver circuit

was underestimated. Misrecognition of primary task.

Failure to identify primary task within time frame to allowsuccessful completion of this portion of the project.

Timing Circuit

Complex Circuit Research

Complex Board Layout

High Speed Circuit


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Special Thanks

Special thanks goes to:

Professor Kwiat

Evan Jeffrey

Mark Smart

Dr. Peter Dragic

Dr. Stephen Bishop

Michael Zhang


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Question and Answer

Documents

Project19 Presentation